>More so than, say, Windows? Really?

significantly so. Windows has a coherent story when it comes to permissions and access. Differentiated out access controls, least privilege, UAC, mandatory integrity control and all configured out of the box.

Without AppArmor or SElinux correctly configured, which it isn't on most desktop distributions in the linux world most of your apps can still read anything, there's little sandboxing. The NT Kernel was designed with an object model in mind so you always had the abilities to have rich descriptions and policies for whatever you're handling where all of that is bolted on unix systems after the fact.